CHARLEVOIX, Quebec — President Trump called for Russia to be readmitted to the Group of Seven industrial nations Friday, reaching out to an adversary as he further scrambled an international summit that has showcased a rift between the United States and its closest allies.

Russia was expelled four years ago after it annexed Ukraine’s Crimea region, and it has since angered U.S. lawmakers and foreign powers over interference in the U.S. presidential election, among other actions. But Trump broke with most other G-7 leaders during the first day of their annual summit here with his call to bring back Russia.

“Russia should be in this meeting,” Trump said Friday in Washington before leaving for the annual two-day summit here. “Whether you like it or not, and it may not be politically correct, but we have a world to run. . . . They should let Russia come back in.”

The split over Russia injected another point of division into an already tumultuous G-7 summit. This annual gathering typically is meant to display a show of unity, but Trump has forced a more combative tone, with messy public feuds breaking out over trade disputes. Most of the foreign leaders at the summit had hoped to use the summit to confront Trump about new tariffs he is imposing on imports, but instead found themselves reacting to Trump’s Russia comments and bombastic Twitter posts.

Italian Prime Minster Giuseppe Conte said he agreed with Trump. British Prime Minister Theresa May said it was important to “engage with Russia,” but she said Russia would have to make changes before readmission could be discussed. Canadian Foreign Minister Chrystia Freeland was more definitive, saying “Russia . . . made clear that it had no interest in behaving according to the rules of western democracies. . . . There are no grounds whatsoever for bringing Russia with its current behavior back into the G-7.”

Russian leaders, meanwhile, largely shrugged off the remarks. “The G-8 needs Russia much more than Russia needs the G-8,” said lawmaker Konstantin Kosachev, chairman of the foreign relations committee in Russia’s upper house of parliament. Kosachev added the country should only rejoin the group only on its own terms — “with sanctions removed and interests respected.”

U.S. intelligence agencies have said they have “high confidence” that Russia interfered in the 2016 election, and part of this year’s G-7 summit was supposed to focus on protecting democracies from foreign meddling. Special counsel Robert S. Mueller III is investigating Russian interference efforts, including whether Trump’s campaign colluded in any way with Russian officials, a probe that has become an obsession for the president.

Trump’s National Security Council was surprised by the president’s call to readmit Russia to the G-7, according to a senior U.S. official who spoke anonymously to describe the administration’s internal dynamic.

Even before the Russia remarks, Trump had effectively upended this year’s G-7 summit by raising the prospect of refusing to sign on to a joint statement with other leaders asserting commonly shared principles and values. And after French President Emmanuel Macron said the other six nations would be willing to move on without the United States, Trump criticized him and Canadian Prime Minister Justin Trudeau — threatening to impose new trade penalties and pull out of the North American Free Trade Agreement.

“We have to change it, and they understand it’s going to happen,” Trump said Friday during an approximately 20-minute impromptu question and answer session with reporters outside the White House. “If we’re unable to make a deal, we’ll terminate NAFTA. We’ll make a better deal.”

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“And I’ll tell you what, it’s what I do. It won’t even be hard. And in the end, we’ll all get along,” Trump said.

But after exchanging public barbs from afar, Trump and other leaders did appear to get along when he finally arrived in this sparkling resort town on the St. Lawrence River. They were all smiles during a group photo of the world leaders.

Trump sounded cheerful and optimistic as he greeted Trudeau, joking that the Canadian leader had suddenly agreed to drop all trade barriers with the United States. Both men laughed. Trump said he thinks there will be a unified statement from all seven leaders when the meeting ends Saturday, but he did not elaborate. He later said he and Trudeau had a “very, very good meeting on NAFTA,” a separate trade issue from Trump’s complaints about the Europeans.

Trump was similarly upbeat as he prepared to sit down for his rescheduled meeting with Macron later Friday.

“We’ve had really a very good relationship, very special. A lot of people wrote a couple of things that weren’t quite true — a little bit accurate, perhaps — we’ve had a little test every once in a while when it comes to trade,” Trump said.

“The United States has had a very big trade deficit for many years with the European Union and we are working it out and Emmanuel’s been very helpful in that regard,” Trump said.

Trump’s suggestion to readmit Russia faced heavy, bipartisan criticism from U.S. lawmakers. Senate Minority Leader Charles E. Schumer (D-N.Y.) accused Trump of “turning our foreign policy into an international joke” while Sen. John McCain (R-Ariz.) — the chairman of the Senate Armed Services Committee and among the first lawmakers to call for Russia’s ejection from what was then the G-8 — slammed the moves, as well.

“Vladimir Putin chose to make Russia unworthy of membership in the G-8 by invading Ukraine and annexing Crimea,” McCain said in a statement. “Nothing he has done since then has changed that most obvious fact.”

In the past several months, Trump has pushed to completely overturn many of the post-World War II institutions put in place to strengthen global ties. These tensions have created immense strain ahead of the summit in Canada, with top leaders questioning if they are in the midst of a transformational disruption brought on by the United States.

“The rules-based international order is being challenged,” European Commission President Donald Tusk told reporters here. “Quite surprisingly, not by the usual suspects but by its main architect and guarantor, the U.S. . . . We will not stop trying to convince our American friends and President Trump that undermining this order makes no sense at all.”

In response to Trump’s proposal for Russia, Tusk said it would only make the group more divisive.

“For today, I think it’s much more important to convince our American partners to strengthen our format as guarantor of world order, than to look for something new, more challenging, more difficult,” he said.

A version of the G-7 or G-8 has existed since the 1970s, designed to build a consensus among world leaders to tackle global challenges. It now consists of the United States, Japan, Britain, France, Germany, Italy and Canada.

The comments marked the latest in declarations in recent days that have completely redirected the focus of the G-7, an organization Trump has shown little regard for since taking office last year.

In an earlier Twitter post, Trump said the United States would emerge victorious if other nations refused to accede to his trade demands, suggesting that he plans to employ a take-it-or-leave-it bargaining position with other world leaders at the summit here.

“Looking forward to straightening out unfair Trade Deals with the G-7 countries,” Trump wrote. “If it doesn’t happen, we come out even better!”

Trump is scheduled to leave the summit early Saturday, an unexpected schedule revision that will pull him out of discussions on climate change. Trump instead will be en route to Singapore to meet with North Korean leader Kim Jong Un.

Many of the world leaders represented here, including Trudeau, have sought to draw Trump toward multilateral institutions despite his “America First” agenda.

But in recent weeks, there have been signs that world leaders have scrapped that approach and now plan to deal with Trump in a more adversarial way, particularly after the White House announced it would begin imposing tariffs on steel and aluminum imports from U.S. allies beginning in June.

Trump is now engaged in trade wars with numerous countries in Europe, North America and Asia, which could affect the flow of hundreds of billions of dollars in goods, including automobiles, agricultural products and technology. He wants Europe and Japan to lower tariffs on imports of automobiles. He wants China to buy more agriculture and energy products from the United States. He is pushing Mexican leaders for a range of changes to NAFTA, and he wants that entire pact to expire after five years.

His view is that other countries have imposed unfair tariffs limiting U.S. imports for decades but that the United States has unwittingly allowed those countries to bring low-cost goods into the country, hurting American companies and workers.

Foreign leaders are aware that as Trump levels trade threats, he faces growing opposition at home. A number of congressional Republicans have expressed outrage, and some are trying to intervene to strip away his powers. Congress so far has not done so, but U.S. business groups — worried about the prospect of higher costs driven by Trump’s trade threats — are pushing Congress to act.

The Kremlin, meanwhile, appears to be enjoying an “I told you so” moment as it watches Trump’s escalating conflict with America’s closest allies. Putin has long spoken about the dangers of a world dominated by the United States, and on Thursday, he said that with Trump’s metals tariffs, Europeans were getting their comeuppance for showing excessive deference to Washington — and getting a taste of the way the United States has long treated Russia.

“Our partners probably thought that these counterproductive policies would never affect them,” Putin said in his annual televised call-in show. “No one wanted to listen, and no one wanted to do anything to stop these tendencies. Here we are.”

Paletta reported from Quebec City. Wagner reported from Washington. Anton Troianovski in Moscow and Josh Dawsey in Washington contributed to this report.

Damian Paletta is White House economic policy reporter for The Washington Post. Before joining The Post, he covered the White House for the Wall Street Journal.

Anne Gearan is a White House correspondent for The Washington Post, with a focus on foreign policy and national security. She covered the Hillary Clinton campaign and the State Department for The Post before joining the White House beat. She joined the paper in 2012.